This paper investigates the shape memory capabilities of semicryst. networks, focusing the attention on poly(ε-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large "temporary" shape configurations, and the easy tailoring of the transformation temps. The materials were prepd. with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicryst. systems was prepd. by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biol. tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystn. temps. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mech. cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory expts. were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a const. load and of a heating/cooling cycle from above melting to below the crystn. temp., leading to a reversible elongation/contraction effect, involving max. strain changes up to about 80%, whose extent may be controlled through the crosslink.
Stefano Pandini, Theonis Riccò, Alberto Borboni, Ileana Bodini, David Vetturi, Danilo Cambiaghi, et al. (2014). Tailored One-Way and Two-Way Shape Memory Capabilities of Poly(ε-Caprolactone)-Based Systems for Biomedical Applications. JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE, 23, 2545-2552 [10.1007/s11665-014-1033-5].
Tailored One-Way and Two-Way Shape Memory Capabilities of Poly(ε-Caprolactone)-Based Systems for Biomedical Applications
TOSELLI, MAURIZIO;
2014
Abstract
This paper investigates the shape memory capabilities of semicryst. networks, focusing the attention on poly(ε-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large "temporary" shape configurations, and the easy tailoring of the transformation temps. The materials were prepd. with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicryst. systems was prepd. by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biol. tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystn. temps. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mech. cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory expts. were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a const. load and of a heating/cooling cycle from above melting to below the crystn. temp., leading to a reversible elongation/contraction effect, involving max. strain changes up to about 80%, whose extent may be controlled through the crosslink.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
